Alan Garner

Alan goes to Las Vegas because he's Doug's future brother-in-law. The bride's father, Sid, lends Doug the family's vintage Mercedes for the trip. The next morning Alan has to confess: he slipped something into the group's drinks, thinking it was mild, so the night would go well. He's also the one who solves a big problem. He counts cards at blackjack and wins $82,400, enough to pay off Chow. At the end he finds Stu's camera and the photos from the night. On the first night, he's the one who takes the group up to the hotel roof to toast with Jägermeister. When Mike Tyson shows up in the suite for his tiger, Alan is the first one knocked out.

In Thailand, Alan comes along because his sister Tracy convinces Doug to bring him. At the airport he's not happy to see Teddy, Stu's 16-year-old brother-in-law, join the group. In the morning he's got a shaved head and a monkey next to him. Then he confesses: he doctored Teddy's marshmallows with medicine to knock him out, but mixed up the bags. An address and a time turn up written on his stomach. In the end Alan gives Stu a Mike Tyson performance as a gift. He's also the one who invited Chow without telling anyone, which is why the gangster turns up at the Bangkok hotel. After the confession, Stu goes after him.

Six months off his ADHD medication, and Alan loses track. He buys a giraffe, it hits a low overpass and causes a pileup. His father, Sid, dies of a heart attack in the argument that follows. The group stages an intervention, and Alan agrees to go to a clinic in Arizona. Later he saves Chow's life, which is why Chow spares the group. Alan turns down the gold he's offered, ends the friendship and stays with Cassie. Six months later he leaves the group before his wedding, but makes clear he still wants to hang out once in a while. His condition for going to Arizona is that Phil, Stu and Doug drive him. As the only one who has spoken with Chow in prison, he's also why the group ends up in the hands of crime boss Marshall, who thinks he knows where Chow is.

Zach Galifianakis plays Alan in all three films. He said he was more embarrassed than anyone by the photo scene at the end of the first one, and offered the director's assistant money to cut it.